More details are we talking fresh water pump or toilet pump?
If toilet pump go to www.thetford-europe.com
use online contact form to send question if the toilet pump as it seems they've stopped download of repair instructions on their toilets.
As far as I know no caravan has an inboard freshwater tank only have external water barrels with some having pump fixed to housing and stowed in the housing just release pump from the tube and 12 volt power lead.
Undo the jubilee clip holding the pipe and release cable from the pump.
Dont test pumps unless they are submerged you'll damage it.
bob
February 2013
Automatic Answer
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howtomendit.com for free repair help, information and advice.
Try fixfault.com to fix caravans/motorhomes.